Bi-directional fixating/locking transvertebral body screw/intervertebral cage stand-alone constructs

ABSTRACT

A bi-directional fixating transvertebral (BDFT) screw/cage apparatus is provided. The BDFT apparatus includes an intervertebral cage including a plurality of internal angled screw guides, a plurality of screw members, and a cage indentation adjacent to the screw guides that independently or supplemented by other screw locking mechanisms prevents the screw members from pulling out of the internal angled screw guides. The internal angled screw guides orient a first screw member superiorly and a second screw member inferiorly. The intervertebral cage is adapted for posterior lumbar intervertebral placement, anterior lumbar intervertebral placement, anterio-lateral thoracic intervertebral placement, or anterior cervical intervertebral placement.

This application is a Continuation-In-Part Application, for whichpriority is claimed under 35 U.S.C. §120, of copending U.S. patentapplication Ser. No. 13/103,994, filed on May 9, 2011 (Attorney DocketNo. 3003/0107PUS8), which is a Divisional of U.S. patent applicationSer. No. 12/054,335, filed on Mar. 24, 2008 (now U.S. Pat. No. 7,972,363B2, issued on Jul. 5, 2011) (Attorney Docket No. 3003/0107PUS1), whichis a Continuation-In-Part of copending application Ser. No. 11/842,855,filed on Aug. 21, 2007 (now U.S. Pat. No. 7,942,903, issued May 17,2011)(Attorney Docket No. 3003/0105PUS1), which is aContinuation-In-Part of application Ser. No. 11/536,815, filed on Sep.29, 2006 (now U.S. Pat. No. 7,846,188 B2, issued Dec. 7, 2010) (AttorneyDocket No. 3003/0104PUS2), which is a Continuation-In-Part ofapplication Ser. No. 11/208,644, filed on Aug. 23, 2005 (now U.S. Pat.No. 7,704,279 issued on Apr. 27, 2010)(Attorney Docket No.3003/0104PUS1), the entire contents of all of the above identifiedpatent applications are hereby incorporated by reference in theirentirety and for which priority of each of the above-identifiedapplications is claimed under 35 U.S.C. §120.

This application also is a Continuation-In-Part Application, for whichpriority is claimed under 35 U.S.C. §120, of copending application Ser.No. 13/084,543, filed on Apr. 11, 2011 (Attorney Docket No.3003/0105PUS2), which is a Divisional of copending application Ser. No.11/842,855, filed on Aug. 21, 2007 (now U.S. Pat. No. 7,942,903, issuedMay 17, 2011)(Attorney Docket No. 3003/0105PUS1), which is aContinuation-In-Part of application Ser. No. 11/536,815, filed on Sep.29, 2006 (now U.S. Pat. No. 7,846,188 B2, issued Dec. 7, 2010)(AttorneyDocket No. 3003/0104PUS2), which is a Continuation-In-Part ofapplication Ser. No. 11/208,644, filed on Aug. 23, 2005 (now U.S. Pat.No. 7,704,279 issued on Apr. 27, 2010) (Attorney Docket No.3003/0104PUS1), the entire contents of all of the above identifiedpatent applications are hereby incorporated by reference in theirentirety and for which priority of each of the above-identifiedapplications is claimed under 35 U.S.C. §120.

This application also claims priority under 35 U.S.C. §119(e) of U.S.Provisional Application No. 61/451,582, filed on Mar. 10, 2011 (AttorneyDocket No. 3003/0107PR07), U.S. Provisional Application No. 61/451,579,filed on Mar. 10, 2011 (Attorney Docket No. 3003/0107PR06), and U.S.Provisional Application No. 61/445,034, filed on Feb. 21, 2011 (AttorneyDocket No. 3003/0107PR05), the entire contents of all of the aboveidentified patent applications are hereby incorporated by reference intheir entirety.

U.S. patent application Ser. Nos. 13/084,543, filed on Apr. 11, 2011(Attorney Docket No. 3003/0105PUS2), 11/842,855, filed on Aug. 21, 2007(Attorney Docket No. 3003/0105PUS1), 11/536,815, filed on Sep. 29, 2006(Attorney Docket No. 3003/0104PUS2), and 11/208,644, filed on Aug. 23,2005 (Attorney Docket No. 3003/0104PUS1), each claim the benefit ofpriority under 35 U.S.C. §119(e) of U.S. Provisional Application No.60/670,231, filed on Apr. 12, 2005 (Attorney Docket No. 3003/0102PR01),and this application hereby incorporates the claim of priority to thisprovisional application under 35 U.S.C. §119(e) from the aforementionedintermediate applications (for which priority of each intermediateapplication is claimed under 35 U.S.C. §120); and the entire contents ofall of the above identified patent applications are hereby incorporatedby reference in their entirety.

FIELD OF DISCLOSURE

The present invention relates to a unique universal bi-directional screw(BDS) system, and in particular its application to the spine, alsoreferred to as bi-directional fixating transvertebral (BDFT) screw/cageconstructs which can be used as stand-alone intervertebral devices whichcombine the dual functions of an intervertebral spacer that can befilled with bone fusion material(s), as well as a bi-directionaltransvertebral bone fixating/fusion screw apparatus. In the posteriorlumbosacral and thoracic spine, intervertebral cage/BDFT screwconstructs can be used as stand-alone devices obviating the need forpedicle screw fixation in many but not all cases. In the anteriorcervical, thoracic and lumbosacral spine, intervertebral cage/BDFT screwconstructs can be used as stand-alone devices obviating the need foranterior or lateral (thoracic and lumbosacral) spinal plating, and/orsupplemental posterior pedicle screw fixation.

BACKGROUND

The history and evolution of instrumented spinal fusion in the entirehuman spine has been reviewed in related applications Ser. No.12/054,335, filed on Mar. 24, 2008, Ser. No. 13/084,543, filed on Apr.11, 2011, Ser. No. 11/842,855, filed on Aug. 21, 2007, Ser. No.11/536,815, filed on Sep. 29, 2006, and Ser. No. 11/208,644, filed onAug. 23, 2005, the contents of which are hereby incorporated byreference in their entirety. Conventionally, the majority of posteriorcervical and almost all posterior thoracic and lumbosacral fusionsurgical techniques are typically supplemented with pedicle screwplacement. Conventionally, the majority of anterior cervical spinalfusions, and many anterio-lateral thoracic, and anterior oranterio-lateral lumbosacral fusions are supplemented with anterior oranterior-lateral spinal plating, and very often, in particular in thethoracic and lumbosacral spine, are supplemented with posterior pediclescrew instrumentation.

Complications of pedicle screw placement in cervical, thoracic andlumbosacral spine include duration of procedure, significant tissuedissection and muscle retraction, misplaced screws with neural and/orvascular injury, excessive blood loss, need for transfusions, prolongedrecovery, incomplete return to work, and excessive rigidity leading toadjacent segmental disease requiring further fusions and re-operations.Recent advances in pedicle screw fixation including minimally invasive,and stereotactic CT image-guided technology, and the development offlexible rods, imperfectly address some but not all of these issues.

Complications of anterior plating in the cervical spine includepotential plate, and/or screw esophageal compression, and misplacedscrews leading to neurovascular injury. Complications of anterior, oranterior-lateral plating in the anterior lumbar spine include potentialdevastating injury to the major vessels due to chronic vascular erosionof the major vessels, or acute vascular injuries due to partial orcomplete plate and/or screw back out. Furthermore, for re-do surgeries,plate removal can be arduous, with potential complications of prolongedesophageal retraction, vascular injury and screw breakage. Recentadvances including diminishing the plate width and/or profile, andabsorbable plates, imperfectly address some but not all of these issues.

Complications of all conventional spinal anterior intervertebral deviceconstructs include the potential for extrusion of these conventionalconstructs in the absence of plating. Hence, these conventionalconstructs are supplemented with anterior plating to prevent extrusion.Complications of posterior lumbosacral intervertebral device constructin the presence or absence of supplemental pedicle screw fixationinclude device extrusion, and potential nerve root and/or vascularinjuries.

SUMMARY

Herein described are a plurality of device embodiments which combine ina single stand-alone construct the dual functions of: a) anintervertebral cage spacer which can be filled with bone fusion materialmaintaining disc height, and, b) a bi-directional fixating/fusiontransvertebral body screw apparatus. These embodiments are described forposterior and anterior lumbar (and anterio-lateral thoracic)intervertebral placement, and anterior cervical intervertebralplacement. The present invention recognizes the aforementioned problemswith prior art apparatus and solves these problems by, among otherthings, improving upon the designs illustrated in the aforementionedrelated applications. The present application provides an advanced andnovel bi-directional fixating transvertebral (BDFT) screw/cage apparatuswith a modified novel cage which has indentations on the upper aspect ofthe screw box adjacent to the internalized angled screw guide. These newindentations have three functions: 1) the indentations distributephysical forces more equally and evenly in the contact interface betweenscrew and box, thereby enhancing the integrity and the strength of thecage itself upon screw insertion thereby diminishing the cage'spossibility of it breaking or cracking, and 2) the indentations allowfor the placement of screws with larger screw heads which furtherincreases the strength of screw engagement, and 3) the indentationsfurther diminish the possibility of screw back out acting as anindependent or supplemental screw locking mechanisms. Although this cageindentation modification precludes the need for an additional screwlocking mechanism, this cage is never the less compatible with and canbe supplemented by any of our three previously described novel screwlocking mechanisms detailed in the related copending applicationsidentified above. This novel interbody cage is also compatible with anyother screw locking mechanism. This cage indentation modification iscapable of functioning as an independent screw-locking mechanism, whichwhen supplemented with any of the described screw locking mechanisms ofany of the related copending applications identified above, or with anyother screw locking mechanism, further increases the strength of thecage, improves screw/cage engagement and further prevents screw backout. All these novel modifications combined further improve theprobability of a solid fusion with the embodiments described herein.

The exemplary embodiments of a bi-directional fixating transvertebral(BDFT) screw/cage apparatus provide as strong or stronger segmentalfusion as pedicle screws without the complications arising from pediclescrew placement, which include misplacement with potential nerve and/orvascular injury, violation of healthy facets, possible pedicledestruction, blood loss, and overly rigid fusions. By placing screwsacross the intervertebral space from vertebral body to vertebral body,engaging anterior and middle spinal columns and not the vertebral bodiesvia the transpedicular route thereby excluding the posterior spinalcolumn, then healthy facet joints, if they exist, are preserved. Becausethe present invention accomplishes both anterior and middle columnfusion, without rigidly fixating the posterior column, the presentinvention in essence creates a flexible fusion.

The present invention recognizes that the very advantage oftranspedicular screws which facilitate a strong solid fusion by rigidlyengaging all three spinal columns is the same mechanical mechanismwhereby complete inflexibility of all columns is incurred therebyleading to increasing rostral and caudal segmental stress which can leadto an increased rate of re-operation.

Transvertebral fusion also may lead to far less muscle retraction, bloodloss and significant reduction in operating room (O.R.) time. Thus, thecomplication of pedicle screw pull out, and hence high re-operation rateassociated with the current embodiment of flexible fusion pediclescrews/rods is obviated. The lumbosacral intervertebral cage/BDFT screwconstructs can be introduced via posterior, lateral, transforaminal oranterior interbody fusion approaches/surgical techniques. Although onecan opt to supplement these constructs with transpedicular screws, therewould be no absolute need for supplemental pedicle screw fixation withthese operative techniques.

The anterior placement of a bi-directional fixating transvertebral(BDFT) screw/cage apparatus according to the embodiments of the presentinvention into the cervical and lumbar spine obviates the need forsupplemental anterior cervical or anterior lumbar plating. The solepurpose of these plates is to prevent intervertebral device extrusion.This function is completely obviated and replaced by the dualfunctioning bi-directional fixating transvertebral (BDFT) screw/cageapparatus, according to the present invention. The embodiments provideimportant advantages of providing a significant savings in operativetime, and reducing or preventing of injuries associated with plating, inparticular esophageal, for example, large and small vessel injuries, andspinal cord nerve root injuries.

Because the embodiments of the bi-directional fixating transvertebral(BDFT) screw/cage apparatus engage a small percentage of the rostral andcaudal vertebral body surface area, multi-level fusions can be performedwith these devices.

Conventionally, failed anterior lumbar arthroplasties are salvaged bycombined anterior and posterior fusions. Intervertebral cage/BDFT screwconstructs may be utilized as a one-step salvage mechanism forfailed/extruded anteriorly placed lumbar artificial discs obviating theneed for supplemental posterior pedicle screws an/or anterior lumbarplating thereby significantly reducing and/or eliminating co-morbiditiesassociated with these other salvage procedures.

Likewise, anterior cervical intervertebral cage/BDFT screw constructplacement can be used to salvage failed anterior cervicalarthroplasties, and re-do fusions without having to supplement withcervical anterior plates, thereby reducing the morbidity of thisprocedure.

In addition, if a patient develops a discogenic problem necessitatinganterior cervical discectomy and fusion at a level above or below apreviously fused and plated segment, the present invention reduces oreliminates the need to remove the prior plate in order to place a newsuperior plate, because the function of the plate is replaced by thedual functioning intervertebral cervical construct, thereby reducing theoperating room time and surgical morbidity of this procedure.

Furthermore, because of the orientation and length of the BDFT screwswithin the intervertebral cage/BDFT constructs, multiple level fusionscan be easily performed.

For example, an exemplary embodiment is directed to an intervertebralcage spacer and bi-directional fixating/fusion transvertebral bodyscrew/cage apparatus. The apparatus includes an intervertebral cage formaintaining disc height. The intervertebral cage includes a firstinternal screw guide and a second internal screw guide adjacent to novelcage indentations which function as independent or supplemental screwlocking mechanisms. The apparatus further includes a first screw memberhaving a tapered end and a threaded body disposed within theintervertebral cage, a second screw member having a tapered end and athreaded body disposed within the intervertebral cage, and a first screwlocking mechanism that prevents the first screw member and the secondscrew from pulling-out of the first internal screw guide and the secondinternal screw guide. Such a screw locking mechanism is described in anexemplary embodiment of the related copending applications identifiedabove.

Another exemplary embodiment is directed to an integral intervertebralcage spacer and bi-directional fixating/fusion transvertebral body screwapparatus, including an intervertebral cage having a plurality ofinternal angled screw guides. The apparatus further includes a pluralityof screw members having a tapered end and a threaded body disposedwithin the plurality of internal angled screw guides of theintervertebral cage, which are adjacent to novel cage indentations whichfunction independently as a screw locking mechanisms or functions intandem with a previously described screw locking mechanism preventingthe plurality of screw members from pulling out of the plurality ofinternal angled screw guides.

Another exemplary embodiment is directed to a method of inserting abi-directional fixating transvertebral (BDFT) screw/cage apparatusbetween a first vertebral body and a second vertebral body. The methodincludes measuring a dimension of a disc space between the firstvertebral body and the second vertebral body, determining that the discspace is a posterior or lateral lumbar disc space, an anterior lumbardisc space, or an anterior cervical disc space, selecting anintervertebral cage based on the measured dimension of the disc spaceand based on the determination of the disc space being the posteriorlumbar disc space, the lateral lumbar disc space, the anterior lumbardisc space, or the anterior cervical disc space, inserting the selectedintervertebral cage into a midline of the disc space until the selectedintervertebral cage is flush or countersunk relative to the firstvertebral body and the second vertebral body, inserting a first screwmember into a first internal screw guide of the selected intervertebralcage, inserting a second screw member into a second internal screw guideof the selected intervertebral cage, screwing the first screw member andthe second screw member into the first vertebral body and the secondvertebral body respectively, confirming a position and placement of theintervertebral cage relative to the first vertebral body and the secondvertebral body, and locking the first screw member and the second screwmember in a final position by embedding a portion of the first screwmember and the second screw member into a previously described screwlocking mechanism and into a novel surrounding cage indentation of theselected intervertebral cage. In the absence of any supplemental screwlocking mechanism, the heads of the first and second screw members candirectly engage the surface of the cage and the adjacent novelindentations directly. These indentations themselves function asindependent or supplemental screw locking mechanisms.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofembodiments of the invention and are provided solely for illustration ofthe embodiments and not limitation thereof.

FIG. 1A illustrates a top view of an anterior cervical cage with novelindentations in a top surface according to an embodiment of theinvention.

FIG. 1B illustrates a side (lateral) view of an anterior cervical cagewith novel indentations in the top surface according to an embodiment ofthe invention.

FIG. 1C illustrates a perspective (oblique) view of an anterior cervicalcage with novel indentations in a top surface according to an embodimentof the invention.

FIG. 2A illustrates a top view of an anterior cervical intervertebralcage/BDFT screw construct according to an embodiment of the invention.

FIG. 2B illustrates a bottom, perspective (bottom isometric) view of ananterior cervical intervertebral cage/BDFT screw construct according toan embodiment of the invention.

FIG. 2C illustrates a side view of an anterior cervical intervertebralcage/BDFT screw construct according to an embodiment of the invention.

FIG. 2D illustrates bottom, perspective (bottom isometric) view of ananterior cervical intervertebral cage/BDFT screw construct according toan embodiment of the invention.

FIG. 2E illustrates a top, perspective, partially exploded (topisometric) view of an anterior cervical intervertebral cage/BDFT screwconstruct according to an embodiment of the invention.

FIG. 2F illustrates a top, perspective, exploded view of an anteriorcervical intervertebral cage/BDFT screw construct with internalizedangled screw guides according to an embodiment of the invention.

FIG. 2G illustrates a top, perspective, exploded view of an anteriorcervical intervertebral cage/BDFT screw construct with internalizedangled screw guides according to an embodiment of the invention.

FIG. 3A illustrates a top view of an anterior Lumbar intervertebral cagewith novel indentations according to an embodiment of the invention.

FIG. 3B illustrates a side view of an anterior Lumbar intervertebralcage with novel indentations according to an embodiment of theinvention.

FIG. 3C illustrates a top, perspective view of an anterior Lumbarintervertebral cage with novel indentations according to an embodimentof the invention.

FIG. 4A illustrates a top view of an anterior lumbar intervertebralcage/BDFT screw construct according to an embodiment of the invention.

FIG. 4B illustrates a bottom view of an anterior lumbar intervertebralcage/BDFT screw construct according to an embodiment of the invention.

FIG. 4C illustrates a front view of an anterior lumbar intervertebralcage/BDFT screw construct according to an embodiment of the invention.

FIG. 4D illustrates a side, perspective view of an anterior lumbarintervertebral cage/BDFT screw construct according to an embodiment ofthe invention.

FIG. 4E illustrates a side perspective view of an anterior lumbarintervertebral cage/BDFT screw construct according to an embodiment ofthe invention.

FIG. 4F illustrates a top, partially exploded view of an anterior lumbarintervertebral cage/BDFT screw construct according to an embodiment ofthe invention.

FIG. 4G illustrates a top, perspective, exploded view of an anteriorlumbar intervertebral cage/BDFT screw construct according to anembodiment of the invention.

FIG. 5A illustrates a top view of a posterior Lumbar intervertebral cagewith novel indentations according to an embodiment of the invention.

FIG. 5B illustrates a side (lateral) view of a posterior Lumbarintervertebral cage with novel indentations according to an embodimentof the invention.

FIG. 5C illustrates a perspective (oblique) view of a posterior Lumbarintervertebral cage with novel indentations according to an embodimentof the invention.

FIG. 6A illustrates top view of a posterior lumbar intervertebralcage/BDFT construct according to an embodiment of the invention.

FIG. 6B illustrates bottom perspective view of a posterior lumbarintervertebral cage/BDFT construct according to an embodiment of theinvention.

FIG. 6C illustrates side view of a posterior lumbar intervertebralcage/BDFT construct according to an embodiment of the invention.

FIG. 6D illustrates perspective view of a posterior lumbarintervertebral cage/BDFT construct according to an embodiment of theinvention.

FIG. 6E illustrates top, perspective, partially exploded view of aposterior lumbar intervertebral cage/BDFT construct according to anembodiment of the invention.

FIG. 6F illustrates top, perspective, exploded view of a posteriorlumbar intervertebral cage/BDFT construct according to an embodiment ofthe invention.

FIG. 7A illustrates a perspective view of an intervertebral cageconstruct according to an embodiment of the invention.

FIG. 7B illustrates another perspective view of an intervertebral cageconstruct according to an embodiment of the invention.

FIGS. 7C(i) and 7C(ii) illustrate top, perspective view of anintervertebral cage construct according to an embodiment of theinvention.

FIG. 7D illustrates a top, perspective, exploded view of a positioningtool/screw guide/box expander.

FIG. 7E illustrates a superior oblique perspective view of thepositioning tool/drill guide/box expander component.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Aspects of the invention are disclosed in the following description andrelated drawings directed to specific embodiments of the invention.Alternate embodiments may be devised without departing from the scope ofthe invention. Additionally, well-known elements of the invention willnot be described in detail or will be omitted so as not to obscure therelevant details of the invention.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. Likewise, the term “embodiments ofthe invention” does not require that all embodiments of the inventioninclude the discussed feature, advantage or mode of operation.

With reference to FIGS. 1A-7E, exemplary embodiments of the inventionwill now be described.

1. Exemplary Medical Device

Referring to FIGS. 1A-7E, the above described problems of theconventional art can be solved in the cervical, thoracic and lumbosacralspines by insertion of multiple embodiments of a bi-directional fixatingtransvertebral (BDFT) screw/cage apparatus into the denudedintervertebral disc space.

For example, FIGS. 1A-1C and 2A-2G illustrate three-dimensional views ofan exemplary embodiment of an anterior cervical intervertebral cage/BDFTconstruct including an intervertebral cage 10 for maintaining discheight. The intervertebral cage 10 can include a first internal screwguide 80 and a second internal screw guide 82. A first screw member 30having a tapered end and a threaded body and a second screw member 40having a tapered end and a threaded body are disposed within the firstinternal screw guide 80 and the second internal screw guide 82 of theintervertebral cage 10.

In this exemplary embodiment, a top portion of a cage 10 can includeindentations 11 adjacent to the internalized screw guides 80, 82, forexample, to distribute physical forces surrounding the screw/cageinterface and/or strengthen the cage 10 (FIGS. 1A-1C). The indentations11 can be formed only in the top surface of the cage 10, or in the topsurface and an edge of the top surface of the cage 10, as illustrated inthe exemplary embodiment. The indentations 11 can function asindependent or supplemental screw locking mechanisms. The cage 10 can besupplemented by, and is compatible with, any screw locking mechanism,for example screw locking member 20, that prevents the first screwmember 30 and/or the second screw member 40 from pulling-out of thefirst internal screw guide 80 and the second internal screw guide 82.The indentations 11 can be, for example, triangular, which maydistribute the force acting on the cage 10, thereby improving orincreasing the strength of the cage 10. As shown in the exemplaryembodiments, the cage 10 can include an opening or slot between theguides 80, 82 for receiving a separate or secondary locking mechanism,as described in more detail below.

The cage 10 also can include indentations 12 on the sides of the cage 10for insertion of the prongs of an insertion device. In anotherembodiment, the sides of the cage 10 can be elliptically contoured whenviewed from the side (e.g., side view of FIG. 2C) to fit into thebi-concave cervical disc space. The embodiment includes two screws 30,40. A first screw 30 is oriented rostrally (superiorly) and a secondscrew 40 is oriented caudally (inferiorly). The cage 10 can include acavity 60 for bone product placement.

The cage 10 includes two built in internalized screw/drill guides 80,82, one for each screw 30, 40, which orient the screws 30, 40bi-directionally in opposite directions. In an embodiment, the cageincludes at least one screw guide 80 or 82 having a predeterminedtrajectory (e.g., preferably having a 25 degree angulation) that maymake placement of all screws equally facile, more amenable tomulti-level placement, and may diminish the need for external drillguides. In other embodiments, the cage includes at least two screwguides 80, 82 having a predetermined trajectory (e.g., preferably havinga 25 degree angulation) that may make placement of all screws equallyfacile, more amenable to multi-level placement, and may diminish theneed for external drill guides.

In other embodiments, the cage can include a screw guide 80, 82 havinganother predetermined trajectory, such as an angulation of substantially25 degrees (e.g., an angulation ranging from 20 degrees to 30 degrees).In other embodiments, the cage can include a screw guide 80, 82 havinganother predetermined trajectory, such as an angulation ranging from 20degrees to 25 degrees, an angulation ranging from 25 degrees to 30degrees, an angulation ranging from 25 degrees to 35 degrees, anangulation ranging from 25 degrees to 35 degrees, an angulation rangingfrom 20 degrees to 40 degrees, etc. The embodiments of the cage caninclude one or more screw/drill guides 80, 82 having different anglesand/or different positions within the cage.

A screw guide tunnel exit 13 is adjacent to the bone cavity, forexample, as illustrated in FIGS. 1C, 2B, 2D, 2E, and 2F. One of ordinaryskill in the art will recognize that the internalized screw/drill guides80, 82 can have different degrees of angulation and/or differentpositions within the cage 10. The built in tunnels of the screw guides80, 82 provide an important advantage of ensuring that only oneprescribed angled trajectory is possible for transvertebral screwplacement. Embodiments of the intervertebral cages can be designed withinternalized screw/drill guides 80, 82 with different angles and/ordifferent positions within the cage. The angle and size of the screws30, 40 make them amenable to single or multi-level placement. Thesuperior and inferior surfaces or edges of the lumbar cage can includeridges 50 or the like to facilitate integration and fusion with superiorand inferior vertebral bodies.

The embodiment also can include a screw locking mechanism 20 which canbe, for example, press-fit to the top of the cage 10. The top of thecage 10 can include a perforation 90 and/or an indentation 70 for eachlocking mechanism 20. Each locking mechanism 20 also can be designed torest and be press-fit into the superior surface of the in-built selfdrilling screw guides 80, 82. The screw locking mechanism 20 can bemanufactured from a variety of materials, such as titanium. When thescrews 30, 40 are turned into the screw locking mechanism 20, the screws30, 40 lock by mechanically indenting the screw locking mechanism 20,thereby preventing back-out or pull-out. The locking mechanism 20 can bereused for a limited number of cycles. In the absence of this lockingmechanism, the screws 30, 40 can be screwed directly into the cage 10with its surrounding indentations 11 which function as independent orsupplemental screw locking mechanisms. The indentations 11 are anevolutionary advance and improvement compared to the apparatusillustrated in the aforementioned related applications. The novelembodiments of the present invention are quite unique and different fromall other conventional screw locking mechanisms. No other conventionalanterior cervical intervertebral cage/BDFT screw constructs are known.

FIGS. 3A-3C and 4A-4G illustrate three-dimensional views of an exemplaryembodiment of an anterior lumbar intervertebral cage/BDFT construct 110having four internalized screw guides 190, 192. In this embodiment, thecage 110 can include indentations 11 on top of the cage 110 laterallyadjacent to the first and fourth internalized screw guides 192 whichfunction as independent or supplemental screw locking mechanisms. Thecage 110 can include additional indentations or slots 12 on both sidesurfaces of the cage 110 for insertion of a prong of an implantationtool, and more particularly, that engage the distal medial oriented maleprotuberance of a lateral griper prong of an implantation tool. The cage110 can be larger than the cervical cage 10 and also can be ellipticallycontoured when viewed from the side (e.g., along the side surfaces ofthe cage 110 in FIG. 4D) to fit into the bi-concave lumbar disc space.The cage 110 can include four (4) horizontally aligned internalizedscrew guides 190, 192 for four (4) screws 130, 140, 150,160. The twolateral (left and right) screws 130, 160 can be oriented inferiorly, andthe two middle screws 140, 150 can be oriented superiorly. The screwguide tunnel exits 13 are illustrated in FIGS. 3C and 4C. The screwguide tunnel exits 13 are in continuity (connected) with the enlargedbone cavity 180. In the embodiment, the orientations of the four screwguides 190, 192 (and screws 130, 140, 150, 160) are selected because oftheir symmetry and inherent stability.

The cage 110 can include a large cavity 180 for bone product placement.The cage 110 can include four built-in internalized screw/drill guides190, 192 (e.g., having a preferred 25 degree angulation, or anotherangulation), one for each screw 130, 140, 150, 160. Other embodiments ofthe intervertebral cage 110 can be designed with internalizedscrew/drill guides 190, 192 with different angles and/or differentpositions within the cage 110. The angle and size of the screws makethem amenable to single or multi-level placement. The superior andinferior surfaces or edges of the cage 110 can include ridges 170 tofacilitate integration and fusion with superior and inferior vertebralbodies. In an embodiment, there are no compartmental divisions in thecavity 180 for bone product placement to maximize the quantity of bonefor fusion.

The cage 110 includes two screw locking mechanisms 120 that can be, forexample, press-fit to the top of the cage 110 (FIG. 4). In theembodiment, one locking mechanism 120 is provided per two screws.However, in other embodiments, one locking mechanism can be provided foreach screw, or one locking mechanism can be provided for two or morescrews. The top of the cage 110 can include a perforation 194 and/or anindentation 196 for each locking mechanism 120. Each locking mechanism120 also can be designed to rest and be press-fit into the in-built selfdrilling screw guides 190, 192. The locking mechanism 120 can bemanufactured from a variety of materials, such as titanium. In thisembodiment, the cage 110 can include indentations 11 at the top of thecage adjacent to each lateral screw 130, 160, as illustrated for examplein FIGS. 3A-4G, which indentations 11 function as independent orsupplemental screw locking mechanisms. When the screws are turned intothe screw locking mechanism 120, they lock by mechanically indenting thescrew locking mechanism 120. The locking mechanism 120 can be reused fora limited number of cycles. In the absence of this locking mechanism,the screw can directly engage the cage indentations 11 adjacent to thescrew guides 190, 192, which function as independent or supplementalscrew locking mechanisms. This design is an evolutionary advance andimprovement compared to the apparatus illustrated in the aforementionedrelated applications. It is quite unique and different from all otherconventional locking mechanisms used for other types of anterior lumbarcages.

The exemplary embodiments of the present invention differ in manysubstantial ways from conventional devices that have been or arecurrently being developed.

For example, a possible conventional device conceivably may includeanterior placed lumbar implants with perforating screws. Such a devicemay include, for example, a horseshoe implant having a plurality ofcylindrical holes with smooth inner surfaces and comprise only one stopfor the heads of the bone screws to be inserted into them. The placementof five cylindrical holes may be oriented within the cage in anon-symmetric manner.

In comparison, the exemplary embodiments of the present invention differin many substantial ways from such devices. For example, the exemplaryembodiments provide a symmetric orientation of the screw holes, as wellas a screw locking mechanism. The exemplary embodiments also include anangulation/trajectory (e.g., a preferred angulation/trajectory) forpreventing pull-out or back-out of the screws that would make placementof all screws in a manner which would lead to maximum stability of theconstruct within the vertebral space, and obviate the need for externaldrill guides, and surgeon trajectory angulation guess work.

In another conceivable conventional device, multiple embodiments oflumbar intervertebral implants may include internally threaded boreholes, without or with a front plate mounted at the front surface of theimplant, and/or with a front plate displaceably configured to movevertically relative to the implant. Conventionally, the preferredborehole axes generally are 35-55 degrees. Conventional devices may havefour screw perforations that are not aligned four in a row; e.g., two ofthe screw holes may be laterally placed on the left, one on top of eachother, the top one with a superior trajectory, and the bottom with aninferior trajectory; and two perforations may be placed on the right,one on top of each other, the top one with a superior trajectory and thebottom one with an inferior trajectory. A possible screw lockingmechanism may be a screw with an external thread matching the internalborehole thread, or spiral springs.

In comparison, the anterior lumbar construct of the exemplaryembodiments differ in many substantial ways from these types of possibleconventional devices. The exemplary embodiments can include a singlecage construct with four (4) internalized drill guides arrangedhorizontally in a row. The middle two screws are oriented superiorly,and the lateral left and right screws are oriented inferiorly. Thissymmetric alignment of screws and orientations within the superior andinferior vertebral bodies (e.g., two middle superiorly projectingscrews, and two laterally projecting inferior screws) make the fixationto the superior and inferior vertebral bodies much more symmetric andthus more stable. In an embodiment, the cage includes a screw guidehaving a predetermined trajectory (e.g., a preferred trajectory of 25degrees) that makes placement of all screws equally facile, moreamenable to multi-level placement, and diminishes the need for externaldrill guides. Furthermore, the exemplary screw locking mechanism, whichis press-fit to the cage, is unique and differs substantially from theconventional approach of matching screw/cage threads or spiral springs.The exemplary cage further has novel indentations adjacent to the screwguides distributing the physical forces at the screw/cage interfacestabilizing the construct and functioning as an independent orsupplemental screw locking mechanism.

FIGS. 5A-5C and FIGS. 6A-6F illustrate three-dimensional views of anembodiment of a posterior lumbar intervertebral cage/BDFT construct. Inthis embodiment, the cage 210 can include indentations 11 on top of thecage 210 that are adjacent to the internal screw guides 270, 280 (FIGS.5A-5C). The indentations 11 can function as independent or supplementalscrew locking mechanisms. The cage 210 also can include indentations 12on both side surfaces of the cage 210 for placement of prongs of animplantation tool. The screws 230, 240 perforate and orient in opposingsuperior and inferior directions. The cage 210 can include a cavity 250for bone product placement. The top and bottom portions of the cage 210can be elliptically contoured to naturally fit into the bi-concaveintervertebral disc space when viewed from the side as shown in FIG. 6C.

The cage 210 can include built-in internalized screw/drill guides 270,280 having a predetermined angled trajectory (e.g., having a preferred25 degree angulation). One of the guides is angled rostrally(superiorly) (e.g., guide 270) and the other caudally (inferiorly)(e.g., guide 280). The intervertebral cages 210 can be designed withinternalized screw/drill guides 270, 280 with different angles and/ordifferent positions within the cage 210. The angle and size of thescrews 230, 240 make them amenable to single or multi-level placement.The screw guide tunnel exit 13 adjacent to the bone cavity 250 isexemplarily illustrated in FIG. 5C. The superior and inferior surfacesor edges of the cage 210 can include ridges 260 to facilitateintegration and fusion with superior and inferior vertebral bodies. Oneof these constructs is placed posteriorly into the intervertebral spaceon the left side, and the other on the right side.

The cage 210 can include a screw locking mechanism 220 that can be, forexample, press-fit to the top of the cage 210. The top of the cage 210can have a perforation 290 and/or an indentation 292 to engage thelocking mechanism 220. The locking mechanism 220 also can be designed torest and be press-fit into the in-built self drilling screw guides 270,280. The locking mechanism 220 can be manufactured from a variety ofmaterials, such as titanium. When the screws 230, 240 are turned intothe screw locking mechanism 220, the screws 230, 240 lock bymechanically indenting the screw locking mechanism 220. The screwlocking mechanism 220 can be reused for a limited number of cycles. Inthe absence of any locking mechanism, the screw head directly engagesthe cage's novel indentations 11 adjacent to the screw guides 270, 280,which indentations 11 can function as independent or supplemental screwlocking mechanisms. The exemplary embodiment of this novelintervertebral cage 210 is an evolutionary advance and improvementcompared to the apparatus illustrated in the aforementioned relatedapplications. The novel cage 210 also is quite unique and different fromother conventional locking mechanisms used for other known cervical andlumbar anterior or posterior plate screws. No other conventionalposterior lumbar intervertebral cage BDFT/screw constructs are known.

2. Exemplary Surgical Method

Exemplary surgical steps for practicing one or more of the forgoingembodiments will now be described.

Anterior cervical spine placement of the intervertebral cage/BDFT screwconstruct (FIGS. 1A-2G) can be implanted via previously describedtechniques for anterior cervical discectomy and fusion. Some but not allof these techniques include, open, microscopic, closed endoscopic ortubular. Fluoroscopic or any other form of visualized guidance can beused for this procedure.

After the adequate induction of anesthesia the patient is placed in asupine position. An incision is made overlying the intended disc spaceor spaces, and the anterior spine is exposed. A discectomy is performedand the endplates exposed. The disc height is measured and an anteriorcervical intervertebral cage of the appropriate disc height, width anddepth is selected. The central cavity 60 of the cage 10 is packed withbone fusion material, autologous bone graft, allograft, alone or incombination with any commercially available bone fusion promotingproduct. The cage 10 is then inserted into the midline of the anteriordisc space routinely until it is flush or countersunk relative to thevertebral body above and below. The BDFT screws 30, 40 are then insertedinto the internalized rostrally (superiorly) and caudally (inferiorly)angled screw guides 80, 82. A drill with or without a drill guide can beused to prepare for screw placement. This is not absolutely necessary.Because the cage 10 has internalized screw guides 80, 82,self-drilling/self-tapping screws 30, 40 of the appropriately selectedlengths can be directly screwed into the vertebral bodies once placedinto the internalized drill-guided angled tunnels. The cage's screwguides 80, 82, which have internalized tunnels, direct the screws 30, 40into the superior and inferior vertebral bodies in the predeterminedangle of the internalized tunnels. There is no other angled trajectoryother than that which is built into the internalized screw guide/tunnel80, 82 of the cage 10 that the screw 30, 40 can be oriented in. Hence,there is no absolute need for fluoroscopic guidance.

Once the surgeon is satisfied with the position and placement of thecage 10, the BDFT screws 30, 40 can then be locked into their finalpositions by the last several turns which embed them into the novelsurrounding cage indentations 11 as well as into the screw lockingmechanism 20 thereby preventing screw blackout. If the surgeon changeshis mind intra-operatively or if in a future date the construct needs tobe removed, the screws 30, 40 can be backed out. The locking mechanism20 has several cycles of use, and thus screws 30, 40 once backed out,can be re-screwed and re-locked. Multiple level placements can beperformed including two, three or more levels if necessary. With thismodification it is not necessarily necessary to supplement with anadditional screw locking mechanism. The novel indentations 11 themselvesfunction as independent or supplemental screw locking mechanisms.Alternatively, one can choose to supplement the cage 10 with this or anyother locking mechanism.

Anterior or anteriolateral placement of thoracic or lumbar spineintervertebral cage/BDFT screw constructs (FIGS. 3A-4E) can be implantedvia previously described surgical techniques for anterior lumbardiscectomy, and transthoracic, anterior-lateral thoracic discectomy.Some but not all of these techniques include, open, microscopic, closedendoscopic or tubular. Fluoroscopic or any other form of visualizedguidance can be used for this procedure.

After the adequate induction of anesthesia and after the anterior spineis exposed a discectomy is performed and the endplates exposed. The discheight is measured and an anterior lumbar (or thoracic) intervertebralcage of the appropriate disc height, width and depth is selected. Thecentral cavity 180 of the cage 110 is packed with bone fusion material,autologous bone graft, allograft, alone or in combination with anycommercially available bone fusion promoting product. The cage 110 isthen inserted into the midline of the anterior disc space routinelyuntil it is flush or countersunk relative to the vertebral body aboveand below. The four BDFT screws 130, 140, 150, 160 are then insertedinto the two middle internalized rostrally (superiorly) and two lateral,caudally (inferiorly) angled screw guides 190, 192. A drill with orwithout a drill guide can be used to prepare for screw placement. Thisis not absolutely necessary. Because the cage has internalized screwguides 190, 192, self-drilling/self-tapping screws 130, 140, 150, 160 ofthe appropriately selected lengths can be directly screwed into thevertebral bodies once placed into the internalized drill-guided angledtunnels 190, 192. The cage's internalized guides 190, 192, which haveinternalized tunnels, direct the screws 130, 140, 150, 160 into thesuperior and inferior vertebral bodies in the predetermined angle of theinternalized tunnels. There is no other angled trajectory other thanthat which is built into the internalized screw guide/tunnel 190, 192 ofthe cage 110 that the screw 130, 140, 150, 160 can be oriented in. Hencethere is no absolute need for fluoroscopic guidance.

Once the surgeon is satisfied with the position and placement of thecage 110, the BDFT screws 130, 140, 150, 160 can then be locked intotheir final positions by the last several turns which embed them intothe novel surrounding cage indentations 11 and the screw lockingmechanism 120, thereby preventing screw blackout. If the surgeon changeshis mind intra-operatively or if in a future date the construct needs tobe removed, the screws 130, 140, 150, 160 can be backed out. The lockingmechanism 120 has several cycles of use, and thus screws 130, 140, 150,160 once backed out, can be re-screwed and re-locked. Multiple levelplacements can be performed including two, three or more levels ifnecessary. Alternatively, in the absence of a screw locking mechanism120, the heads of the screws 130, 140, 150, 160 can be embedded directlyinto the cage indentations 11 which function as independent orsupplemental screw locking mechanisms, thereby preventing screw backout.

Implantation of the posterior lumbar intervertebral cage/BDFT screwconstructs (FIGS. 5A-6F) can be performed via previously describedposterior lumbar interbody fusion (PLIF) or posterior transforaminallumbar interbody fusion (TLIF) procedures. The procedures can beperformed open, microscopic, closed tubular or endoscopic techniques.Fluoroscopic guidance can be used with any of these procedures.

After the adequate induction of anesthesia, the patient is placed in theprone position. A midline incision is made for a PLIF procedure, and oneor two parallel paramedian incisions or a midline incision is made forthe TLIF procedure. For the PLIF procedure, a unilateral or bilateralfacet sparing hemi-laminotomy is created to introduce the posteriorlumbar construct into the disc space after a discectomy is performed andthe space adequately prepared.

For the TLIF procedure, after unilateral or bilateral dissection anddrilling of the inferior articulating surface and the medial superiorarticulating facet the far lateral disc space is entered and acircumferential discectomy is performed. The disc space is prepared andthe endplates exposed.

The disc height is measured and a posterior lumbar intervertebralcage/BDFT screw construct (FIGS. 5A-6F) of the appropriate disc height,width and depth is selected. The central cavity 260 of the cage 210 ispacked with bone fusion material, autologous bone graft, allograft,alone or in combination with any commercially available bone fusionpromoting product. Then one construct/cage 210 is placed on either rightor left sides, or one construct/cage 210 each is placed into left andright sides. The constructs/cages 210 are inserted such they are flushor countersunk relative to the superior and inferior vertebral bodies.In addition to the central cavities 260 that are packed with boneproduct, the intervertebral space in between the constructs/cages 210can also be packed with bone product for fusion.

The BDFT screws 230, 240 are then inserted into internalized rostrally(superiorly) and caudally (inferiorly) angled screw guides 270, 280. Adrill with or without a drill guide can be used to prepare for screwplacement. This is not absolutely necessary. Because the cage 210 hasinternalized screw guides 270, 280, self-drilling/self-tapping screws230, 240 of the appropriately selected lengths can be directly screwedinto the vertebral bodies once placed into the internalized drill-guidedangled tunnels. The cage's internalized guides 270, 280, which haveinternalized tunnels, direct the screws 230, 240 into the superior andinferior vertebral bodies in the predetermined angle of the internalizedtunnels. There is no other angled trajectory other than that which isbuilt into the internalized screw guide/tunnel 270, 280 of the cage 210that the screw 230, 240 can be oriented in. Hence, unlike posteriorplacement of pedicle screws 230, 240 there is no absolute need forfluoroscopic or expensive and cumbersome, frameless stereotactic CTguidance.

Once the surgeon is satisfied with the position and placement of thecage(s) 210, the BDFT screws 230, 240 can then be locked into theirfinal positions by the last several turns which embed them into thenovel cage indentations 11 and the screw locking mechanism 220 therebypreventing screw back out. If the surgeon changes his mindintra-operatively or if in a future date the construct needs to beremoved, the screws can be backed out. The locking mechanism has severalcycles of use, and thus screws once backed out, can be re-screwed andre-locked. Alternatively in the absence of this screw locking mechanism220, the screw heads can be directly embedded into the cage indentations11 which can function as independent or supplemental screw lockingmechanisms, thereby preventing screw back out. Multiple level placementscan be performed including two, three or more levels.

The exemplary embodiments may provide effective and safe techniques thatovercome the problems associated with current transpedicular basedcervical, thoracic and lumbar fusion technology, as well as anteriorcervical, thoracic and lumbar plating technology, and for manydegenerative stable and unstable spinal diseases. These exemplaryembodiments could replace many pedicle screw and anterior plating basedinstrumentation in many but not all degenerative spine conditions.

The speed and simplicity of placement of anterior and posterior lumbarintervertebral cage/BDFT screw constructs, and placement of anteriorcervical cage/BDFT screw constructs according the exemplary embodiments,far exceeds that of current pedicle screw and anterior spinal platingtechnology. Furthermore, these exemplary devices have markedlysignificantly decreased risk of misguided screw placement and hencedecreased risk of neurovascular injury, and blood loss. The lumbar andcervical intervertebral cage/BDFT screw constructs according to theexemplary embodiments all would have decreased recovery time, and morerapid return to work time compared to pedicle screw, and platingtechnology. These exemplary devices with great probability lead tosimilar if not equal fusion rates, with substantially less morbidity,and hence, overall, make them a major advance in the evolution of spinalinstrumented technology leading to advances in the compassionate care ofthe spinal patient.

FIGS. 7A, 7B, 7C(i), and 7C(ii) illustrate an exemplary embodiment ofexemplary cage 200. These features are not limited to the cage 200, andcan be incorporated into any cage according to any of the embodimentsdescribed herein. As shown in FIGS. 7C(i) and 7C(ii), the screw guidescan be positioned within four (4) quadrants I, II, III, IV.

For example, the intervertebral cage can include a wall having an entryopening of the first integral screw guide and an entry opening of thesecond integral screw guide, wherein the wall of the cage can includefour quadrants delineated by a first axis and a second axis each lyingin a plane of the wall, and the first axis is at a right angle withrespect to the second axis, wherein the four quadrants include a firstquadrant, a second quadrant, a third quadrant, and a fourth quadrant,wherein the first quadrant and the fourth quadrant are opposed to thesecond quadrant and the third quadrant with respect to the first axis,and the first quadrant and the second quadrant are opposed to the thirdquadrant and the fourth quadrant with respect to the second axis,wherein the first quadrant is diagonally opposed to the third quadrant,and the second quadrant is diagonally opposed to the fourth quadrant,and wherein one of a majority of an area of the entry opening of thefirst integral screw guide is in the first quadrant and a majority of anarea of the entry opening of the second integral screw guide is in thethird quadrant; and the majority of the area of the entry opening of thefirst integral screw guide is in the second quadrant and the majority ofthe area of the entry opening of the second integral screw guide is inthe fourth quadrant.

In an embodiment, the intervertebral cage can include a wall having anentry opening of the first integral screw guide and an entry opening ofthe second integral screw guide, wherein the wall has four quadrantsdelineated by a first axis and a second axis each lying in a plane ofthe wall, and the first axis is at a right angle with respect to thesecond axis, wherein the four quadrants include a first quadrant, asecond quadrant, a third quadrant, and a fourth quadrant, wherein thefirst quadrant and the fourth quadrant are opposed to the secondquadrant and the third quadrant with respect to the first axis, and thefirst quadrant and the second quadrant are opposed to the third quadrantand the fourth quadrant with respect to the second axis, wherein thefirst quadrant is diagonally opposed to the third quadrant, and thesecond quadrant is diagonally opposed to the fourth quadrant, andwherein one of a center of the entry opening of the first integral screwguide is in the first quadrant and a center of the entry opening of thesecond integral screw guide is in the third quadrant; and the center ofthe entry opening of the first integral screw guide is in the secondquadrant and the center of the entry opening of the second integralscrew guide is in the fourth quadrant.

FIG. 7D illustrates an embodiment of an external drill/screw guide-boxexpander which assists in screw trajectory of the exemplary cage 200.The cage 200 can be a cage according to any of the embodiments describedherein, or an expanding cage, in which case an expanding Allen keycomponent can be used. The device can include, for example, an Allen key501 (e.g., for an expandable cage), a spring 502, a handle 503, a griper504, and a screw guide 505.

FIG. 7E illustrates a superior oblique view of the screw guidedemonstrating insertions or grooves 509 for griper prong 506 of thegriper 504 in FIG. 7D, built-in trajectory guides 511, 512 forinsertions of screws, and an opening 514 for an Allen key.

The griper 504 has griper prongs (e.g., medially oriented maleprotuberant extensions) 506 which insert into grooves 509 of the screwguide 505 and lateral slots (e.g., 12) of the cage, thereby perfectlyaligning them.

Hence, according to the exemplary embodiments, a cage can be providedthat has internal screw guides which have no gaps, and furthermore aninsertion tool can be provided that has an external screw guide thatfurther precisely guides the screws through the external tool screwguide, then into the internal implant screw guide guaranteeing theprecise predetermined angulation of the screws. The combination theinternal and external screw guides can create a long tunnel for a screwto enable a predetermined trajectory.

It is noted that the same trajectory can be provided by only with theinternal box screw guides; however, one of ordinary skill will recognizethat having the external screw guides as part of the tool furthermaintains the precise angle trajectory. The screw guide positions withinthe four (4) quadrants I, II, III, IV conform to the screw guidepositions within the four (4) quadrants I, II, III, IV of the screw box.

With reference to the drawings, it will be understood that an embodimentof the indentations or recesses for the screw holes in any of theexemplary cages can be configured such that the screw heads will restentirely within a peripheral side of a surface of the top portion of thecage (i.e., top surface). In this embodiment, the direction of the screwtunnel is from an anterior surface to a posterior of the top surface ofthe cage (i.e., the non-adjacent side).

In another embodiment, the indentations or recesses for the screw holescan be configured such that the screw heads will rest entirely withinthe peripheral side of the top surface of the cage. In this embodiment,the screw hole guide passes through the anterior-posterior axis of thetop surface. The guides core circumference for the screw thread issurrounded by the lateral wall masses, and surrounded by mass from thefront and rear surfaces (i.e., walls) of the cage.

In yet another embodiment, the indentations or recesses for the screwholes can be configured such that a recess for the screw holes areentirely within the peripheral side of the top surface of the box. Inthis embodiment, there is a through-hole for a screw which iscounter-bored to keep the screw head within an outer surface boundary ofthe cage and in a direction to prevent the screw from avoiding the frontor rear surfaces of the cage.

In yet another embodiment, the indentations or recesses for the screwholes can be configured such that a recess for the screw holes isentirely within the peripheral side of the front wall of the cage Inthis embodiment, the tunnel for the screws is such that when the screwfirst enters, the screw will be surrounded by mass from the lateralsides and mass from the upper and lower sides of the wall. The screwwill exit at the posterior end of the peripheral wall.

With reference to the drawings, it will be understood that an embodimentof the indentations or recesses for the screw holes can be configuredsuch that a position of the screws is suitable for posterior lumbarscrew holes.

For example, in an embodiment, the screw holes can be diagonal to eachother along a transversal line. The transversal line can be defined asthe line that would diagonally intersect and bypass the space betweenthe recess for the screw holes.

In another embodiment, the screw holes can be diagonally opposed and lieon a congruent angle to each other from the intersecting transversalline.

In another embodiment, the recess for the screw holes can be diagonaland perpendicular to each other within the outer plane.

In another embodiment, the recess for the screw holes can be diagonaland symmetrically constrained within the outer wall of the cage.

While the foregoing disclosure shows illustrative embodiments of theinvention, it should be noted that various changes and modificationscould be made herein without departing from the scope of the inventionas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the embodiments of the inventiondescribed herein need not be performed in any particular order.Furthermore, although elements of the invention may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

1-87. (canceled)
 88. An intervertebral combination internal screw guideand fixation apparatus configured to be inserted into a disc spacebetween a first vertebral body and a second vertebral body and toprovide fusion of the first vertebral body to the second vertebral bodyvia biological bone fusion and screw fusion, the apparatus comprising:an intervertebral spacer including a top wall, a bottom wall, and firstand second sidewalls, wherein the intervertebral spacer defines: an openspace between the top, bottom, first, and second sidewalls capable ofreceiving bone filling for biological bone fusion, a first slot on afirst outer side of the first sidewall, a second slot on a second outerside of the second sidewall of the two sidewalls, wherein the secondslot is positioned opposite of the first slot, wherein the first slot ispositioned along a first centerline axis that bisects the first sidewall and wherein the second slot is positioned along a second centerlineaxis that bisects the second side wall, a first internal screw guidehaving a first entry opening and a first exit opening, the first entryopening of the first internal screw guide formed at least partially in atop surface of the top wall and the first exit opening formed at leastpartially in a bottom surface of the top wall and at least partially ina first side surface of the top wall, a second internal screw guidehaving a second entry opening and a second exit opening, the secondentry opening of the second internal screw guide formed at leastpartially in the top surface of the top wall and the second exit openingformed at least partially in the bottom surface of the top wall and atleast partially in a second side surface of the top wall so as to extendin a direction different than that of the first internal screw guide, anindentation in the top surface of the top wall extending between atleast a portion of the first internal screw guide and the secondinternal screw guide, and a hole extending into the top wall at an anglethat is perpendicular to the top surface of the top wall and at aposition that is located in the indentation between the first internalscrew guide and the second internal screw guide, a first screw having afirst screw head and a first threaded body that is sized and configuredto be inserted through the first internal screw guide; a second screwhaving a second screw head and a second threaded body that is sized andconfigured to be inserted through the second internal screw guide; and ascrew locking mechanism positioned in the indentation of theintervertebral spacer and extending at least partially into the hole.89. The apparatus of claim 88, wherein the screw locking mechanism has acentral portion sized and configured to be inserted in the hole and hasfirst and second side portions extending perpendicular to the hole so asto engage the first and second screws and secure the first and secondscrews in position when the first and second screws are inserted intothe first and second internal screw guides.
 90. The apparatus of claim88, wherein the screw locking mechanism comprises means for preventingthe first and second screw from pulling out of the first and secondinternal screw guides.
 91. The apparatus of claim 88, wherein the screwlocking mechanism comprises a first curved portion extending toward thefirst internal screw guide in engaging contact with the first screw whenthe first screw is inserted in the first internal screw guide and asecond curved portion extending toward the second internal screw guidein engaging contact with the second screw when the second screw isinserted in the second internal screw guide.
 92. The apparatus of claim88, wherein the intervertebral spacer further defines: a third internalscrew guide having a third entry opening and a third exit opening, thethird entry opening of the third internal screw guide formed in the topsurface of the top wall and the third exit opening formed at leastpartially in the bottom surface of the top wall and at least partiallyin the first side surface of the top wall, and a fourth internal screwguide having a fourth entry opening and a fourth exit opening, thefourth entry opening of the fourth internal screw guide formed in thetop surface of the top wall and the fourth exit opening formed at leastpartially in the bottom surface of the top wall and at least partiallyin the second side surface of the top wall.
 93. The apparatus of claim88, wherein the screw locking mechanism comprises a narrow portion thatis positioned in the hole and a wider portion that is positioned in theindentation, wherein the narrow portion extends from the wider portioninto the hole.
 94. The apparatus of claim 88, wherein the hole is acircular hole.
 95. The apparatus of claim 88, wherein the intervertebralspacer further defines: a first circular side hole extending into thefirst outer surface of the first sidewall; and a second circular sidehole extending into the second outer surface of the second sidewall,wherein the second circular side hole is positioned opposite of thefirst circular side hole, wherein the first slot and the first circularside hole are both positioned along the first centerline axis thatbisects the first side wall and wherein the second slot and the secondcircular side hole are both positioned along the second centerline axisthat bisects the second side wall.
 96. The apparatus of claim 88,wherein the top wall is continuous with the first and second sidewalls.97. The apparatus of claim 88, wherein the open space extends from aninner surface of the first sidewall to an inner surface of the secondsidewall and extends from an inner surface of the top wall to an innersurface of the bottom wall.
 98. The apparatus of claim 88, and furthercomprising means for facilitating integration and fusion with superiorand inferior vertebral bodies.
 99. The apparatus of claim 98, whereinthe means is positioned at least partially on the first side surface ofthe top wall between the top surface of the top wall than the first exitopening.
 100. The apparatus of claim 88, wherein the first side surfaceof the top wall is patterned with a plurality of surface features tocreate a first rough side surface, wherein at least some of theplurality of surface features are positioned on the first side surfacebetween the top surface of the top wall and the first exit opening. 101.the apparatus of claim 100, wherein the plurality of surface featuresare patterned all the way to the top surface of the top wall such thatat least one or more of the surface features are positioned on the sidesurface of the top wall adjacent to the top surface of the top wall.102. The apparatus of claim 92, wherein the first side surface of thetop wall is patterned with a plurality of surface features to create afirst rough side surface, wherein at least some of the plurality ofsurface features are positioned on the first side surface between thetop surface of the top wall and each of the first and third exitopenings, wherein the second side surface of the top wall is patternedwith the plurality of surface features to create a second rough sidesurface, wherein at least some of the plurality of surface features arepositioned on the second side surface between the top surface of the topwall and each of the second and fourth exit openings.
 103. The apparatusof claim 88, wherein a diameter of the hole is smaller than a diameterof the first and second internal screw guides.
 104. the apparatus ofclaim 88, wherein the open space extends continuously from the firstsidewall to the second sidewall.
 105. A system comprising: The apparatusof claim 88; and a tool for manipulating and inserting the spacer intothe disc space between the first vertebral body and the second vertebralbody to provide fusion of the first vertebral body to the secondvertebral body via biological bone fusion and screw fusion, the toolcomprising: an elongate shaft; first and second gripper prongspositioned such that the first gripper prong engages the first slot ofthe spacer and the second gripper prong engages the second slot of thespacer when the tool engages the spacer; and a screw guide forcontrolling a direction of the first screw and the second screw that areinserted into the first internal screw guide and the second internalscrew guide of the spacer, wherein the screw guide is positioned betweenthe plurality of prongs with distal ends of the prongs extendingdistally past the screw guide.
 106. The apparatus of claim 88, andwherein the locking mechanism comprises titanium.
 107. The apparatus ofclaim 88, and further comprising means for performing supplemental screwlocking.